Best Ecommerce Cart Software For Clothing Shop?

Im building my first online shop selling shoes (and some clothing). I would like the users to be able to filter products by sub-categories. For example; Size, Colour, Price, and Brand etc, as shown in the image below:

Click Here to view the webpage. Any idea what software they used to do this?

If not, which other ecommerce cart software would be good to use? Ive had a quick look at Cubecart and Magento, but not sure if they can do this? I wouldnt mind buying software (up to about £400) if needed.

Try zencart, the two sites in my sig are both zencarts. The software is open source - although when you see how good it is you'll want to contribute something i'm sure - and the community forums are top notch.

I'm currently using nopCommerce and I think it's great. Its fairly easy to skin and give you tons of control over your store. It's also search engine friendly (which is always good for an e-commerce site!)